Office lighting is most commonly provided by means of ceiling ‘troffers’, which are (typically rectangular) light fixtures designed to accommodate fluorescent or LED light sources, and configured to fit into a modular dropped ceiling grid. Troffers typically comprise reflective and/or diffusive optical components to modulate direction or character of emitted light.
One disadvantage of troffer-based lighting solutions is that light is typically distributed uniformly across an illuminated space, leading to much wasted light, where light is directed to areas or regions within the space (for example in between desks or workstations in an office) where illumination is not required (at least at the same intensity).
Additionally, in the case of illumination within an office for instance, the level or intensity of the light provided to each desk or workstation cannot be independently controlled, since light is distributed in a uniform, non-discriminatory way across all regions within the illuminated space. Independent control of lighting for different regions in a space would be useful in many cases, for example to enable temporary increase of light level for older or sight-impaired workers or users, while keeping light level relatively lower for other workers/users. Locally increased light (temporary or otherwise) might also be of advantage for performing precision tasks for instance, or it may be useful to change light level lower when performing screen-based tasks (to avoid glare) and higher when performing paper-based tasks.
Currently known troffer-based lighting systems are also typically expensive to install (due to the requirement to run electronic cabling to across the ceiling to each troffer) and require relatively high levels of maintenance (fixing broken lamps/sensors, changing commissioning settings, fixing commissioning errors). As mentioned above, known troffer systems do not enable local tailoring of illumination characteristics, such as brightness, colour, directionality or for implementing individual timing or scheduling (such as to fit with individual circadian rhythms).
As an alternative to troffer-based lighting systems, it is known to use ground-based light sources, configured to project upwards onto the ceiling. This creates a bright spot on the ceiling, whose reflection then illuminates the space directly beneath. Ground-based illumination such as this provides far greater flexibility in terms of changing local light levels and characteristics. Light can be provided in a highly localised manner, with each workstation or desk for instance provided with an individual ground-based light source, which can be individually adjusted.
However, for efficiency, such systems typically require the ceiling to be either painted white, or to be fitted with a dedicated reflector panel. A white ceiling leads to light being spread in unwanted directions, and therefore wasted.
A reflector panel is known from EP-2711773. The known reflector panel comprises an array of micromechanical reflectors that are disposed to selectively direct portions of light from a light source to a selected target, wherein the array of reflectors is continuously steerable. The known reflector panel is suitable for providing composed illumination for still or video photography, and it may be integrated with a compact camera into a cellular telephone, a tablet computer, a laptop computer, a digital still-image camera, or a digital video-image camera.
However, as alternative for ceiling-based lighting such as a troffer-based lighting system, the known reflector panels offer very limited degree of control over the directionality of the reflected light. To achieve illumination at a particular location, the ground-based light sources must be fixed at a precise relative location, in order to achieve the required reflection angle. Often, this is not practical, due to constraints imposed by the layout of the office (or other space), and hence light is typically cast onto areas or regions which are not precisely congruous with workstation locations. This limits possibilities for individualised control of provided lighting.
There is a need therefore for a lighting system and associated apparatus capable of providing improved control over the directionality of illumination.